Mount Prospect, Illinois 7 Day Weather Forecast

Wx Forecast - Wx Discussion - Wx Aviation

724
FXUS63 KLOT 020824
AFDLOT

Area Forecast Discussion
National Weather Service Chicago/Romeoville, IL
324 AM CDT Thu Apr 2 2026

.KEY MESSAGES...

- Waves of showers and storms expected today. Some of the storms
  this afternoon may become severe. There is also a threat for
  tornadoes between 5 and 9 PM CST, especially along/west of
  I-39.

- Strong gusty south winds, gusting at times up to 45 to 50 mph
  are expected this afternoon, even outside of thunderstorms.

- There is another threat for severe weather Friday and
  Saturday, though the threats are conditional on placement of
  boundaries and system arrival timing.

- A transition toward a quieter, but cooler, pattern is on
  track to arrive early next week.

&&

.DISCUSSION...
Issued at 324 AM CDT Thu Apr 2 2026

Forecast concerns continue to focus on the threat of showers
and thunderstorms, some of which are likely to become severe
this afternoon and evening. Outside of thunderstorms, strong
southerly winds are also expected to develop as a warm front
lifts north across the area later this morning. With gusts
expected to be in the 45 to 50 mph range for a period today, we
have opted to hoist a wind advisory for all but far northwestern
IL for this afternoon through early evening.

Early this morning, a large region of showers, and embedded
non- severe thunderstorms, continue to stream northeastward
across the Midwest into our area in advance of a rapidly
maturing surface cyclone over western Kansas. It appears the
primarily corridor for these showers and storms this morning
will primarily be focused along and northwest of the I-55
corridor, with more scattered activity farther to the southeast.
Warm rain processes appear to be aiding in the efficiency of
this activity to produce localized heavier rainfall rates and
amounts. In fact, some of the recent MRMS precipitation
estimates indicate the presence of narrow southwest-to-northeast
corridors of nearly inch per hour rates with some of this
activity currently lifting into northern IL. While this does not
look to materialize into a significantly flooding threat across
northern IL this morning, the continued likelihood for locally
moderate to briefly heavy rainfall may result in some minor
flooding, particularly in ditches and low spots. Significant
ponding can also be expected on area roads into the morning
commute.

The parent surface cyclone will track northeastward today,
generally along a corridor from far northwest MO late this
morning, across northeastern IA into southwestern WI late this
afternoon into early this evening. As it does, the surface
frontal boundary in place across far southern IL will race
northward as a warm front this morning. A period of very low
clouds, and possibly even a short period of fog, will be likely
early this morning just ahead of the warm frontal boundary.
Otherwise, while the front may not clear far northeastern IL
until sometime early this afternoon, a majority of the area will
become entrenched within the windy, warm and very moist warm
sector of the cyclone for the afternoon and evening hours today.
Strong southerly winds in the warm sector will push
temperatures into 60s and low 70s this afternoon as surface
dewpoints surge into the low to mid 60s. Also, as mentioned
above, the likelihood of gusty southerly winds up to 45 to 50
mph this afternoon did prompt us to hoist a wind advisory for
all but far northwestern IL. The current advisory is set to end
at 7 PM this evening, though rather gusty southwest winds may
continue beyond this time.

In the wake of this mornings showers and storms, a narrow
corridor of destabilization is expected to expand northward into
eastern IA and northwestern IL, just in advance of the surface
low and beneath the region of better mid-level height
falls/cooling associated with the approaching negatively tilted
impulse. This is expected to foster ample conditions for
additional scattered surface based storm development by mid to
late this afternoon across eastern IA, just ahead of the
approaching cold front. The kinematic environment in which the
storms develop will favor supercells, and the oblique
orientation of the deep layer shear vector relative to the
surface front suggests these initial storms may be semi-discrete
for a time as they progress into northwestern IL. The presence
of strong low-level wind shear will also favor tornadoes with
these storms into early this evening. The greatest tornado
threat late this afternoon into early this evening expected from
eastern IA into northwestern IL and southwest WI. This area
matches very well with the current SPC day 1 10% tornado threat
area. These storms should progress eastward across northern IL
into a region of weaker instability. In spite of this, a
continued severe threat, possibly transitioning more to damaging
wind gusts with isolated tornadoes, may persist for a few hours
in the evening due to the strongly favorable kinematic
environment ahead of the front. The storm threat will end from
west-to-east through the evening.

These late afternoon and evening storms should have the
greatest severe risk for the area (including tornadoes).
However, there may end up being a localized damaging wind risk
across much of northern IL with some of the early to mid
afternoon (1-4pm) storms expected to move across the area well
in advance of those talked about above. These storms should
become nearly surface based and rooted in the warm sector early
this afternoon, and hence have access to 50+ kt winds not too
far above the surface. Locally heavy rainfall will also likely
accompany these storms.

KJB

Friday into Saturday:

Forecast thinking during this period has not changed from
previous thinking.

Yet another upper-level shortwave is poised to dive into the
central Plains tonight into Friday, causing the cold front
this evening to stall somewhere in the Ohio River Valley
Friday. A surface pressure col will move over the area Friday
morning before pressure falls in the Midwest allow for southerly
flow to redevelop and the warm front to lift back northward.
Exactly how far northward the front will retreat is an item of
low confidence, and will be important to the forecast for
temperatures by mid-afternoon. In scenarios where the front gets
hung up somewhere across central Illinois and Indiana, many
areas may remain in the 50s for much of the day. Meanwhile, any
areas south of the front will have the potential to jump back up
into the 70s.

Friday afternoon, forecast soundings depict minimal capping
along the warm front leading to concerns for the development of
convection. With the upper-level wave remaining well to our
west, shear profiles along the front will be modest and largely
driven by low-level directional changes across the front itself.
Taken together, the conceptual pattern appears supportive of
low-topped supercell structures with a threat for funnel clouds
and weak tornadoes along the warm front. At this point, the
front is favored to be somewhere south of I-80, and perhaps even
south of US-24. Pin-pointing the location of the front will be
a priority in future forecast packages.

The upper-level shortwave is expected to shift eastward into
the Great Lake Friday night into Saturday likely accompanied by
a band of showers and thunderstorms. The unfavorable diurnal
arrival time of the peak forcing suggests the severe weather
threat should be low in our area, though any slowing of the wave
would be cause for concern for one last window of severe
thunderstorms in our area (This stretch from mid-March through
now has been relentless!). At any rate, Saturday will feature
nearly steady temperatures in the 50s to around 60 as cold air
advection works into the region behind the cold front.

Borchardt


Sunday Onward:

In the wake of this system, a period of drier weather is
expected to close out the weekend as a surface high moves into
the Mississippi Valley. However, the upper trough is expected to
stall over the Great Lakes which will result in nearly constant
northwest flow resulting in seasonably cool high temperatures
in the 40s to lower 50s for Sunday and again on Monday.

The upper trough is forecast to start pushing east of the Great
Lakes on Monday as an upper ridge builds over the central
CONUS. As a parting gift a final shortwave is progged to round
the backside of the trough Monday night which could bring us one
more period of rain showers during this timeframe, That said,
there is a lot of variability in guidance as to how much
moisture will be available Monday night as the wave moves
through so there is a chance that the rain avoids northern IL
and northwest IN all together. For now though will advertise a
20-40% chance for rain. After Monday night, the upper ridge will
be moving into the Great Lakes which will promote dry
conditions for the middle of next week with temperatures
moderating towards more seasonable values in the mid to upper
50s.

Yack

&&

.AVIATION /06Z TAFS THROUGH 12Z FRIDAY/...
Issued at 110 AM CDT Thu Apr 2 2026

Forecast concerns for the terminals...

- Rain and lower IFR ceilings will prevail across the terminals
  tonight. Though, an occasional lightning strike cannot be
  ruled out at times.

- 20-30% chance for a period of LIFR ceilings and possibly
  visibilities due to fog at the terminals around daybreak as
  the warm front lifts through.

- Rounds of showers and thunderstorms expected on Thursday
  especially during the afternoon and evening. Some storms could
  be severe with damaging winds, hail, and tornadoes possible.

- Gusty south-southwest winds Thursday with gusts peaking around
  30-40 kts especially at the Chicago terminals.


An upper trough ejecting out of the central Plains this evening
with its associated surface low over northeastern KS and
northwestern MO. Attached to this surface low is a warm front
that stretches from central MO across southern IL and southern
IN. Ahead of these features, a modest low-level jet has
developed and has generated a broad area of rain showers that is
spreading across northern IL and northwest IN. These showers are
expected to prevail through the night and will result in 3-5
mile visibilities and IFR ceilings. While lightning coverage
with this activity has been sparse, there have been a couple of
clusters (near KVYS and in central MO) that have lightning and
if these storms continue to utilize the instability would move
over the Chicago area terminals around 07z and 10z respectively.
Right now confidence is higher in lightning maintaining with the
storm cluster near KVYS so have introduced TEMPOs at DPA, ORD,
and MDW for these storms, but confidence is much lower with the
later wave currently in MO so have opted to hold off on thunder
mention with these.

Heading into Thursday morning, the actual warm front will lift
into the area which will result in a southeasterly wind shift
and ceilings lowering further into the LIFR category (around
300-500 ft AGL). There is also a modest signal in guidance for a
period of fog to develop along the front which could result in
sub-mile visibilities. However, confidence on if this fog will
actually develop remains low so have opted just tease the
potential with prevailing IFR visibilities for now. Behind the
front another round of showers and thunderstorms is expected to
move through the area Thursday morning with the greatest
coverage of thunder expected across western and northwest IL.
Additional rounds of showers and thunderstorms are expected
Thursday afternoon and evening across virtually the entire area.
The afternoon rounds of storms could also be severe with
damaging winds, hail, and even tornadoes possible, though the
greatest severe threat (especially for tornadoes) is currently
in western and northwest IL.

While ceilings Thursday afternoon are expected to improve a bit
into the lower end VFR range, winds behind the warm front will
become quite gusty. In fact, south-soutwesterly gusts are
expected to peak in the 30-40 kt range from 20z through at least
00z Thursday evening.

Finally, a cold front will push through the area Thursday
evening and bring the showers and thunderstorms to a close.
However, winds behind the cold front look to remain breezy out
of the west-southwest through Thursday night with gusts around
20-25 kts. Ceilings will also lower back to MVFR Thursday
evening with the potential for some IFR ceilings at times
Thursday night.

Yack

&&

.LOT WATCHES/WARNINGS/ADVISORIES...
IL...Wind Advisory from 1 PM this afternoon to 7 PM CDT this
     evening for ILZ006-ILZ010-ILZ011-ILZ012-ILZ013-ILZ019-
     ILZ020-ILZ021-ILZ103-ILZ104-ILZ105-ILZ106-ILZ107-ILZ108.

     Wind Advisory from 10 AM this morning to 7 PM CDT this evening
     for ILZ023-ILZ032-ILZ033-ILZ039.

IN...Wind Advisory from 10 AM CDT /11 AM EDT/ this morning to 7 PM
     CDT /8 PM EDT/ this evening for INZ001-INZ002-INZ010-
     INZ011-INZ019.

LM...Small Craft Advisory until 1 PM CDT this afternoon for the IL
     and IN nearshore waters.

     Small Craft Advisory from 9 PM this evening to 4 AM CDT Friday
     for the IL and IN nearshore waters.

     Gale Warning from 1 PM this afternoon to 9 PM CDT this evening
     for the IL and IN nearshore waters.

&&

$$

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